A wheat kernel is comprised of three principal component parts: (i) a fibrous outer layer or wheat bran, (ii) germ, and (iii) endosperm. The endosperm contains both wheat starch, enclosed within starch granules, and wheat gluten. Wheat starch enjoys a wide variety of applications, including use as a constituent in adhesives and paper making, as a food thickener and as a source of dextrose sugar and other food sweeteners. Wheat gluten, in its naturally occurring "vital" form, can be admixed with water to form a cohesive, pliable mass, or dough, which is useful in the preparation of bakery goods.
Methods for the refining of whole grain wheat to recover wheat starch and/or wheat gluten are known. In some refining processes, the whole wheat kernel is dry milled, i.e., by crushing, grinding, squeezing, or the like, to separate the kernel into fiber (bran), wheat germ and wheat endosperm. The endosperm fraction or fractions are milled further to provide wheat flour and the flour, in turn, is treated to separate wheat starch and wheat gluten. In a typical commercial procedure, the wheat flour is formed into a dough or batter, and as the dough or batter is mechanically worked to form a consolidated mass comprised of wheat gluten, the wheat starch is elutriated from the glutenous mass. Such processes are not entirely satisfactory because much of the wheat starch is often lost in the dry grinding and dough washing operations, and starch yields are correspondingly low. Moreover, the wheat germ and fiber (bran) are often discarded during such dry milling processes, which is inefficient.
In still other wheat refining processes, whole wheat kernels are first pre-soaked in water or an acidic solution such as sulfurous acid to soften the kernel, the soaked kernel is then wet milled to loosen or separate the branny outer layer from the endosperm, and the endosperm is processed further to separate wheat starch and/or wheat gluten. See, for example, the disclosures in Rodgers, et al U.S. Pat. No. 3,851,085, Galle, et al, U.S. Pat. No. 3,958,016 and Rao, et al, U.S. Pat. Nos. 3,790,553; 3,979,375 and 3,891,613. Because the wheat grain is very compact and has a hard outer shell, such processes usually require long soaking (steeping) times, thus tying up equipment for extended periods of time. Moreover, separation of the wheat starch from the wheat gluten is often achieved by the use of dough washing procedures, which is an inefficient means for obtaining wheat starch.